[MOS] TODAY - Modern Optics and Spectroscopy Seminar with Andrew H. Marcus

[Christine Brooks]

There will be a Modern Optics and Spectroscopy Seminar held TODAY at 12pm in 56-154

**Please note location**

Andrew H. Marcus
University of Oregon

“Spectroscopic studies of exciton-coupled cyanine dimers in model DNA fork constructs”

Understanding the properties of electronically interacting molecular chromophores, which involve internally coupled electronic-vibrational motions, is important to the spectroscopy of many biologically relevant systems. We apply linear absorption, circular dichroism (CD), and two-dimensional fluorescence spectroscopy (2DFS) to study the polarized collective excitations of coupled cyanine dimers (composed of Cy3), which are rigidly positioned within the opposing sugar-phosphate backbones near the junctions of double-stranded (ds) – single-stranded (ss) DNA fork construct. We show that the exciton-coupling strength of the (Cy3)2-DNA construct can be systematically varied with temperature below the ds – ss DNA denaturation transition. We interpret spectroscopic measurements in terms of the Holstein-Frenkel vibronic dimer model, from which we obtain information about the local conformation of the (Cy3)2 dimer, as well as the degree of static disorder experienced by the cyanine monomer and dimer probes locally within their respective DNA fork junction environments. The properties of these cyanine labeled DNA constructs that we have determined suggest that these systems may be employed as useful models to test fundamental concepts of protein-DNA interactions, and the role of electronic-vibrational coherence in electronic energy migration within exciton-coupled bio-molecular arrays.

Refreshments will be served immediately following the seminar


Christine Brooks
Administrative Assistant
Massachusetts Institute of Technology
Department of Chemistry
77 Massachusetts Ave, 6-333
Cambridge, MA 02139
p: 617.253.7239
e: cbrooks at mit.edu<mailto:cbrooks at mit.edu>

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